ceiling boards

Webster's Dictionary (GCIDE)

1.(Arch.) (a) The inside lining of a room overhead; the under side of the floor above; the upper surface opposite to the floor. (b) The lining or finishing of any wall or other surface, with plaster, thin boards, etc.; also, the work when done. [1913 Webster]

2.(Naut.) The inner planking of a vessel. [1913 Webster]

Camp ceiling. See under Camp.

Ceiling boards, Thin narrow boards used to ceil with. [1913 Webster]